Air in a crack repair????

[terryalex29]

I did a crack today. It was about 15" long it went up and then turned down in the opposite direction from the first line. It filled great all the way and when I got ready to cure it I noticed that the first part of the crack had gotten air in it. How do you prevent this and if it happens how do you fix it. It turned out good overall but I would have liked it to be better. I know that it was long, but the customer wanted me to try. Thanks for your help. Terry

[Delta Kits]

Any movement of the glass after it has been filled can lead to air reentering the crack. When I do long cracks, after every six inches or so I cover the crack with curing tape, completely flush against the windshield...That helps a bit.

Also, sliding bridges and moving crack expanders can cause this as well. We recommend using a crack expander, but leaving it attached and not moving it until the resin is cured.

Even pushing the uv light on can cause the shield to flex and introduce air, so on long cracks it's better to either hold the light (a pain) or use your other bridge's vacuum cup, put it below the crack, and let the uv light sit on top, without using it's suction cups...

In short, any flexing at all can lead to air bubbles.

[desertstars]

Terry.

You can't fix it unless you drill back into the unfilled area and proceed to fill the unfilled area. (After it had already cured, I presume.)

In this case, I suspect you either did not maintain pressure along the crack, slid too quckly with your bridge assembly, or went short on resin which resulted in loss of same mentioned pressure. (Assuming some minute contamination wasn't at fault.)

Jeff's observations are valid with two exceptions in my humble opinion.

A flush application of the curing tape rather than a cured ridge as I prefer.

And slowly sliding the bridge assembly while maintaining resin pressure which I prefer.

I don't necessarily disagree with Delta in this regard.

The subject as to how to repair cracks is as complicated as the differences
in DNA profiles and certainly warrants more discussion.

[terryalex29]

Thank you for your help, is there a way to get the air out prior to curing?

[screenman]

I will often pop a bullseye at the start of the crack about one inch in from the edge of the screen assuming it is a edge crack and place a injector over this with slight pressure on it. I will then fill the crack by sliding from as close as possible to that injector to the end of the crack also placeing curing film as often as possible I then cure leaving the original injector in place until I just have the last bit left to cure. Then I will remove that as carefully as possible and cure.